According to this https://www.sciencedirect.com/science/article/abs/pii/S0190962213010554, and this, https://onlinelibrary.wiley.com/doi/full/10.1111/bjd.14499, sensitivity and specificity for BCC as a whole is pretty good. Predictive values for the different types of BCC is pretty good in some variants but not so much in others.
Kassi et al. (2012) does state that there is low yield in some cases as you pointed out in your quote and was highlighted in the Reddit cross-post.
Again, pointed out in Reddit, you are sucking up individual cells and not taking a piece of tissue and therefore it can have an incredibly low yield and sometimes produce false negative results.
With the figures ...